A dental crown is a tooth-shaped "cap" that is placed over a tooth -- to cover the tooth to restore its shape and size, strength, and improve its appearance.
The crowns, when cemented into place, fully encase the entire visible portion of a tooth that lies at and above the gum line.
Temporary versus permanent:
Temporary crowns can be made in your dentist's office, whereas most permanent crowns are made in a dental laboratory. Typically, temporary crowns are made of an acrylic-based material or stainless steel and can be used as a temporary restoration until a permanent crown is constructed by a lab.